Israeli military authorities say they were not responsible for a blast last Friday at a beach in the Gaza Strip that killed eight Palestinians, including seven members of one family.

The Israeli military inquiry says the blast was caused by an explosive buried in the sand on the beach, and not by Israeli artillery or by Israeli Navy vessels firing from offshore.

Senior Israeli military officers say fragments of shrapnel taken from Palestinians wounded in the attack, who were treated at Israeli hospitals, do not match the 155-millimeter shells used by the Israeli Army. Speaking at a Tel Aviv news conference late Tuesday, Israel's Defense Minister Amir Peretz said as tragic as the incident was, Israel is not responsible.

Israel's defense minister says initial suspicions by Israeli authorities that they were not responsible for the blast have been borne out by the evidence accumulated in the investigation.

Israeli military authorities also say aerial photographs they have taken, and a timeline of their firing, also indicates that their shelling had stopped by the time the explosion occurred on the beach.

Palestinian officials have rejected the conclusions. Saeb Erekat, a senior official responsible for negotiations with Israelis, told VOA he believes Israeli authorities are trying to blame Palestinians for what happened, which he says could result in similar incidents happening in the future.

"First of all, the Palestinians do not have any weapons capable of such precision and such effectiveness that can massacre seven people in one shot," he said. "Secondly, I believe that the Israeli side should have pointed out who was really responsible to make sure that such incidents will not reoccur. Now they want to escape the responsibility, and these crimes may reoccur and that is dangerous and alarming."

An independent investigation conducted by the U.S. based Human Rights Watch, which sent an investigator to Gaza, has found that the injuries suffered by the Palestinians were inconsistent with a mine-blast as suggested by Israeli authorities in earlier statements. The Human Rights Watch investigator says he believes evidence points to an Israeli artillery shell as causing the deaths and injuries on the beach, but that something else could have also caused the blast.

The blast, which killed the seven members of the Ghalia family last week, led to an upsurge in violence in the area. Hamas militants immediately called off a 16-month ceasefire they had been observing, and resumed launching Quassam rocket attacks against targets in southern Israel. Since then there have been almost daily exchanges of rocket fire by Palestinian militants and retaliatory attacks by Israeli forces along the Israel-Gaza border.